The World of Colorants

The world would probably be a rather drab and mundane place without the vivid spectrum of colors visible to the human eye. Color provides a radiant, dazzling visual experience; from the neutral hues of gray to the bright and radiant shades of yellow. A family of chemical compounds called colorants are one of the primary ways in which colors are created and infused into human-made objects. It includes two subcategories- dyes and pigments. Dyes are soluble organic substances that can be mixed with water and applied to materials like fabrics. Pigments, on the other hand, are insoluble compounds often found in paints, inks, ceramics, and plastics. Numerous different pigments are organic substances as well. They are applied in a dispersion via a number of different methods.

Natural Dyes

Natural dyes have been used for thousands of years by civilizations around the world from a variety of different organic sources. Many might be surprised to learn that bugs (tiny scale insects in particular) were once a major source of colorants, and they’re still used to a lesser extent. They were typically found in food colorings, fabrics, cosmetics, and more. Records indicate that Cleopatra used items with insect-derived dye. A significant portion of these dyes were of a red esque hue. They are made by harvesting the bugs and crushing them to extract the red dye from their remains. The specific species used by cleopatra and other ancient societies is unconfirmed, but many hypothesize that Oak-Kermes scale insects were the bug of choice in ancient Egypt. People groups in Central and South America have also manufactured dyes from insect remains for the past few centuries, particularly scale insects called cochineal. Farming the bugs, harvesting them, and collecting the dye is even a legitimately profitable line of work in some rural areas. Cochineal dyes are marketed under a variety of labels such as cochineal, carmine, carminic acid, Natural Red 4, and E120; amongst others. The stuff is extremely stable during cooking and other processes, which makes it an ideal substance for mass manufacturing. Cochineal dye is often used as a food colorant in sausage, artificial crab, yogurt, juices, and more. It can also be found in cosmetic products like blushes and lipsticks. The dyes are non-toxic, but a very select minority of people might be allergic to the compounds. For that reason, the FDA has required products containing scale insect dyes to state the ingredients clearly on the label to properly inform a potential buyer that the item contains a known allergen.

Synthetic Dyes

In the modern age, most dyes are actually synthetic products. Synthetic dyes offer a broader range of colors and are less expensive than the original natural dyes. Some natural dyes are now increasingly rare and expensive, but synthetic dyes can be made in the same color and at a significantly lower price. The first synthetic dye was created in 1856 by William Henry Perkin, who created a dye derived from coal tar. They can be applied to the material in many different ways, but the most common method is to simply immerse the material into the dye solution itself. Dyes that fuse with the material and sticks to it by forming durable chemical bonds are called direct dyes. The question of whether or not a dye will work like this is rooted in dye itself as well as the material to be dyed. Some dyes will bond directly with some fabrics, and others will not. Conversely, mordant dyes are ones that require the addition of another chemical in order to attach itself to the fabric. Mordant dyeing begins with applying the mordant first, which bonds with the fabric and dries. Once the mordant has dried and formed a chemical bond with the fabric, the dye is then added. The dye will be able to stick to the mordant and the fabric will then take on the color of the dye.

Pigments

Pigments are made and applied in a completely different way than dyes. In many cases, the pigments are thick viscous materials, which means that they’re more difficult to apply. They always consist of multiple different ingredients- the pigment itself, the vehicle through which the color is applied to the material, and often a thinning agent such as turpentine to make the application to the material easier. When the pigment compound {the pigment, the vehicle, and the thinning agent} is applied to the material, it undergoes a series of chemical changes. The thinning agent will eventually evaporate, with the pigment and the vehicle evenly distributed on the surface of the material. Then the vehicle oxidizes, which changes it from a thick liquid to a solid form. By this time, the particles of the pigment are fully embedded with the vehicle, which is now solid. As a result, it forms a thin but tough layer of color that is effectively bonded to the material.

The Importance of Colorants

Colorants are an extremely important and widespread product across many industries and are found in a multitude of household products used by millions of people every day. They have both aesthetic and practical purposes. Countless different products and items would be unrecognizable without their trademark color provided by dyes and pigments. Ever since they were discovered in bugs thousands of years ago all the way up to the modern age in which colorants were synthesized, dyes and pigments have fulfilled a vital role in manufacturing.